Question

Atomicity of ozone molecule is:
A.1
B.2
C.3
D.4

Answer 1

Hint: We can define atomicity as the total number of atoms that composes a molecule. If we simply say, it is the number of atoms present in a molecule i.e. it can be monatomic, diatomic, triatomic, etc. Such as, each molecule of oxygen is composed of two oxygen atoms. Thus, the atomicity of oxygen is 2. Similarly, we can find out for ozone molecules.

Formula used:
\[Atomicity = \dfrac{{molecular\,\,mass\,\,of\,\,{O_3}}}{{atomic\,\,mass\,\,of\,\,O}}\]

Complete step-by-step answer:
We know that ozone has the molecular formula of \[{O_3}\] . It is another form of an oxygen element with one extra oxygen atom in it. Atomicity is the total number of atoms present in one molecule as we saw in oxygen, there are two atoms, so its atomicity will be 2.
Similarly, we can determine the atomicity of ozone molecules. We know that one ozone molecule is composed of three atoms. Therefore, its atomicity will be three. In other words, we can say that ozone is a triatomic molecule whereas oxygen is a diatomic molecule.
There is an alternative way to find out the atomicity i.e., we can find out the number of oxygen atoms in ozone from the ratio of molecular mass of ozone to the atomic mass of an oxygen atom.
 \[Atomicity = \dfrac{{molecular\,\,mass\,\,of\,\,{O_3}}}{{atomic\,\,mass\,\,of\,\,O}}\]
We know the atomic mass of oxygen is 16 gm. and the molecular mass of ozone is 48 gm.
On putting these values in the formula given above, we get
 \[Atomicity = \dfrac{{48}}{{16}} = 3\]
Therefore, the atomicity of oxygen in ozone molecules is three.

Hence, the correct option is (C).

Additional information:
We can explain the structure of ozone molecules by resonance. It is found in the upper atmosphere and formed by the action of ultraviolet radiation on oxygen by splitting oxygen into oxygen atoms which further reacts with \[{O_2}\] to form ozone.

Note: Ozone is a homonuclear molecule as it contains only one type of atom, so it becomes easier to count the total number of atoms in homonuclear molecules as compared to heteronuclear molecules, which have more than one type of atoms. Therefore, in such cases, divide the mass of the molecule by its respective atom to get the atomicity.